128395691 has 2 divisors, whose sum is σ = 128395692. Its totient is φ = 128395690.

The previous prime is 128395639. The next prime is 128395693. The reversal of 128395691 is 196593821.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 128395691 - 2¹⁰ = 128394667 is a prime.

Together with 128395693, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (128395693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64197845 + 64197846.

It is an arithmetic number, because the mean of its divisors is an integer number (64197846).

Almost surely, 2^128395691 is an apocalyptic number.

128395691 is a deficient number, since it is larger than the sum of its proper divisors (1).

128395691 is an equidigital number, since it uses as much as digits as its factorization.

128395691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 116640, while the sum is 44.

The square root of 128395691 is about 11331.1822419375. The cubic root of 128395691 is about 504.4871976486.

The spelling of 128395691 in words is "one hundred twenty-eight million, three hundred ninety-five thousand, six hundred ninety-one".